1. Field of the Invention
The present invention relates to an automatic thin-section manufacturing system which manufactures thin sections by thinly cutting an embedded block containing embedded therein a biological sample.
2. Background Art
Conventionally, a microtome has been known in general as a tool to use in preparing thin section slide samples for physicochemical experiments and microscopic observations. The thin section slides are prepared by fixing thin sections about several micrometers (for instance, from 3 μm to 5 μm) in thickness on a substrate such as a glass slide. A generally employed method for preparing a thin section sample using a microtome is described below.
An embedded block is prepared by first subjecting a formalin-fixed biological sample taken out from living bodies, laboratory animals, and the like to paraffin substitution, and then solidifying the periphery thereof with paraffin to prepare a solid block. Then, preliminary cutting is carried out by setting the embedded block in a microtome, i.e., a thin sectioning apparatus especially designed for this purpose. By preliminary cutting, the surface of the embedded block is smoothed, and the biological sample, which is intended to be subjected to the experiment or observation, is brought into a state that is exposed to the surface.
Main cutting is carried out upon completion of preliminary cutting. In this process step, the cutting blade of the microtome slices the embedded block to provide ultra-thin sections at the predetermined thickness. Thin sections can be obtained in this manner. In such a case, more accurate observation data can be made available by slicing the embedded block as thin as possible, since the thickness of the thin section can be brought near to that of a living cell. Accordingly, it is required to manufacture thin sections as thin as possible.
After the main cutting, thin sections thus obtained are flattened in the flattening process. More specifically, because the thin sections obtained by the main cutting are sliced so thin, they are apt to be wrinkled or curled (U-shaped). Thus, flattening step is necessary to remove the wrinkles or curls from the thin sections.
In general, flattening is performed by using water and hot water. Firstly, the thin section obtained by main cutting is released in water to set afloat. In this manner, large wrinkles or curls of the thin section can be removed while preventing the paraffin, which contains embedded therein the biological sample, from sticking to each other. The thin section is then floated in hot water. The remaining wrinkles and curls can be thus removed from the thin section, because the thin sections are more easily extended in hot water.
After finishing hot flattening, the thin section is mounted on a substrate by scooping it onto a substrate such as a slide glass. If flattening is insufficient at this point, the substrate having the thin section mounted thereon is wholly placed on a hot plate and the like to further apply heat. In this manner, the thin section can be further flattened.
Finally, the substrate having mounted thereon the thin section is dried by placing it inside an oven. By drying, the water adhered to the thin section during flattening evaporates, and the thin section is fixed on the substrate. As a result, a thin section slide sample can be obtained.
Since most of the manufacturing processes described hereinbefore require highly skilled technique and experience, in general, the process is committed to a manual operation of a skillful technician. Recently, however, in order to reduce the load of the operator, a section-slides manufacturing apparatus which automatically carries out a part of the process is provided (see, for example, JP-A-2004-28910).
The section-slides manufacturing apparatus automatically operates the process of preparing thin section slide samples by cutting an embedded block set in the apparatus, transporting the thus prepared thin section on a carrier tape to transfer the thin section on a slide glass, and flattening the thin section by entirely transferring the slide glass having thereon the thin section to the flattening apparatus. The burden of the operator can be somewhat reduced by using the section-slides manufacturing apparatus.
However, the section-slides manufacturing apparatus described in the JP-A-2004-28910 above still had the following problems to be solved.
Firstly, in order to manufacture high quality thin section sample slides by thinly cutting the embedded block to manufacture the thin sections, the thin sections should be sectioned at a predetermined thickness and with the cutting face as flat and clean as possible. Accordingly, the operators must be particularly aware of not only the cutting speed and the like, but also the edge of the cutting blade. If thin cutting should be carried out with a blunt-edged cutting blade, difficulties were found in thinly cutting the embedded block into thin sections of desired thickness (for instance, from 3 μm to 5 μm). Furthermore, there were possibilities of breaking the thin sections in some cases. Moreover, there was a possibility of applying too high a load to compress (deform) the thin section, thereby making it unfeasible to recover (flatten) in the subsequent flattening process step. Thus, in order to avoid such inconveniences, the operator must routinely exchange the cutting blades.
However, since a large number of embedded blocks must be processed, and because plural thin sections are cut out from a single embedded block, the cutting blades had to be frequently exchanged. In particular, generally in case of main sectioning, the cutting blade was changed to a new one because a sharp edge was necessary. Accordingly, the operator had to bear great burden.
It is possible to somewhat shift the load from the operators by using the apparatus described in the JP-A-2004-28910; yet, however, the operator had to exchange the cutting blades. Thus, the operators were still hard-pressed, and the apparatus was not easy for handling.
Furthermore, the cutting blade is generally set at a predetermined rake angle. Thus, in case of exchanging the cutting blade, the cutting blade must be kept supported, or it slides down by the gravity and cannot be set at the regular position. Thus, the operator had to hold the cutting blade carefully lest it should slide off during the exchange operation. This laid additional burden on the operator.
The present invention has been accomplished under such circumstances with an objective to provide an automatic thin-section manufacturing system capable of manufacturing thin sections by thinly cutting an embedded block while automatically exchanging the cutting blades disposed at such a state that the predetermined rake angle is maintained, thereby minimizing the burden of the operator.